The present invention relates to device encapsulation. In device fabrication, one or more device layers are formed on a substrate. The layers are sequentially deposited and patterned to create features on the surface of the substrate. The layers can be patterned individually and/or as a combination of layers to form the desired features. The features serve as components that perform the desired functions, creating the device.
One type of device which is of particular interest is a light emitting diode (LED). LEDs can have a variety of applications. For example, a plurality of LED cells or pixels can be formed on a substrate to create a pixelated LED device for use as a display, such as a flat panel display (FPD).
Typically, an LED pixel comprises one or more functional layers sandwiched between two electrodes to form a functional stack. Charge carriers are injected from both electrodes. These charge carriers recombine in the functional layer or layers, causing visible radiation to emit. Recently, significant advances have been made utilizing organic functional layers to form organic LEDs.
To protect the LED pixels from the environment such as moisture and/or air, the device is encapsulated with a package. Conventionally, LED packages comprises various kinds of cavity packages. The cavity packages typically comprise mounting a lid on the substrate. The cavity protects the organic LED pixels from being damaged by the package since they are very sensitive to pressure. Further, the cavity also enables the placement of desiccant material to cope with finite leakage rate of the device.
Flexible devices formed on thin or flexible substrates are being contemplated for new applications, such as flexible displays. However, conventional device packaging is not amenable to being flexible. This makes it difficult to satisfy the flexibility requirement of flexible devices, particularly those having relatively large surface areas such as displays.
As evidenced from the above discussion, it is desirable to provide an effective package for devices, particularly those formed on thin or flexible substrates.